Pneumatic tire



D@n 16, 1947. J. F. PURDY 2,432,630

PNEUMATIC TIRE Filed Aug. 8, 1942 3 Sheets-Sheet 1 ln/vanter,

Dec. 16, 194.7. J. F. PURDY PNEUMATIC TIRE Filed Aug. 8, 1942 3 Sheets-Sheet 2 7/ next outer and 70 inner/nos! cmd Lum,

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J. F. PURDY PNEUMATIC TIRE Dec. 16, 1947.

Filed Aug. 8, 1942 3 Sheets-Sheet I5 P r i 8 ,v v A ,//4 n w/m Patented Dec. 1c, 1941 John F. may, Akron, ohio, signoria wingfoot Corporation. Wilmington, Del., a corporation of Delaware Application August 8, 1942, Serial No. s545086 13 claims; (ci. 15e-356i This invention relates to pneumatic tires and methods of making the same, and, more particularly, is concerned with pneumatic tires including a plurality of vvrubberized cord fabric plies having the cords of all of the plies of the tire sub- Jected to substantially uniform tension in use, and with methods of building the tires to achieve this result.

For many years it has been recognized that it is highly advisable to have uniform Vply cooperation in a pneumatic tire. As early as 1904, Patent No. 778,496 was granted to A. H. Marks dis. closing awtire carcass built up from a plurality of plies of fabric, and with the .innermost ply cut on a bias angle of 45 degrees and each succeeding ply having a greater angle with respect to the great circle of the tire to thereby assertedly decrease elasticity of each succeeding ply and provide, uniform stress in the several plies of the tire. Patents Nos. 1,374,505 and A1,493,674 to Ernest Hopkinson are` also concerned with assertedly providing uniform ply cooperation throughout a pneumatic tire, and Hopkinson like Marks, taught the idea of increasing the angle between the cords and the great circle` qf the tire outwardly of the plies of the tire, Again, Elliot Patent No. 2,225,042 is concerned with the same problem of providing uniform loading of the cords of the various plies in a tire carcass and discloses and claims the idea of employing a plurality of groups of plies, each group having a pair of adjacent plies with cords running in the same direction and used in cooperation with a second pair of adjacent plies having parallel cords but extending in an opposite direction to. the cords of the first set of plies.

Although there have been various suggestions, such as those above discussed, to overcome the problem of providing a pneumatic tire carcass having uniform ply cooperation, nevertheless it has been the standard practice in building a pneumatic tire to cut the cord fabric plies on the same bias angle. It is well understood that when the several plies of a pneumatic tire are cut on the same bias angle, but are superimposed one upon the other in the building of the tire the difference in diameter of the several plies, and the shaping of the tire from the drum or core built form to the' vulcanized finished form provides a tire structure in which the angle between the cords of each plyand the great circle of the tire increases inzeach ply outwardly from the innermost ply. In other Words, a tire carcass built from cord fabric cut on the same bias angle in the finished tire provides a structure similar to that of Marks and Hopkinson, namely, a structure in which the angle between the cords of each ply and the great circle of the tire increases radially outwardly of the tire.

I have discovered that prior art proposals to provide uniform tensioning of the various plies and cords in a pneumatic tire serve to accentuate rather than relieve the difilculty of non-.uniformity and of stress concentration. Similarly, I have found that building a tire carcass on a drum from cord fabric plies cut on the same bias angle, but finishing up. in the built and shaped tire at progressively greater angles outwardly of the plies and with respect t0 the great circle of the tire, accentuates the non-uniform loading of the various plies. Usually, as long as the number of plies in a tire carcass is kept to four, or at the most six, the standard practice of using the same bias angle on each one of the several plies in the carcass does not'give rise to objectionably different stresses in the several plies of the tire carcass. Also, if cord fabric possessing relatively high stretch characteristics is employed the resiliency of the cords of the fabric of the several plies is suciently great so that objectionable non-uniformity of stress is not readily apparent in the tire carcass. However, when low stretch rubberized cord fabric is employed to build a tire carcass (and low stretch cord fabric is widely used today), or when a tire carcass is built up of a.

' considerable plurality of plies, for example ten or more, in the manner which has become so common in recent years in the manufacture of large truck and other vehicle tires (certain large airplane and earth-mover tires include as many as thirty-two or more plies) then the problem of non-uniformity of ply` loading becomes a very serious one and will result, when the tire is shaped from built to vulcanized form or when inated, in a tire structure in which certain of the plies are so stressed that they.will either break or pull out at the beads, and in which other plies 0f the tire are so free of stress that the cords therein may be without tension and may be wrinkled.

Itis the general object of my invention to avoid and overcome the foregoing and other dilculties of and objections to known and suggestedprior art practices for assertedly relieving non-uniformity of stress in the several plies of a tire carcass by the provision of a tire having a rubberized cord fabric ply carcass which in use will substantially uniformly tension all of the cords in all of l the plies of the tire.

Another object of my invention is the provision o f a pneumatic tire having uniform cooperation among the plies of the tire when inated and in service, uniform pressure load on all plies, and a uniform distribution of shearing stresses among the plies.

Another object of my invention is the provision of a .pneumatic tire made from a plurality of rubberized cord fabric plies, and with the cord angle and cord tension among all the plies being so closely controlled that in all cases a cord tension in the inated tire may be obtained which is considered optimum for the particular fabric at spaced points. Therefore, the term cord fabric used in the tire, and so that no cord in the iinished tire is either over-tensioned or under-tensioned but isdo'lng substantially its full share and no more when the tire is operated for the purpose desired. Another object of my invention is the provision of improved methods for producing a pneumatic tire having substantially uniform ply cooperation.

Another object of my invention is the provision of a pneumatic tire wherein the cord path of the cords of each ply is such that stresses due to loading and inflation pressure will be uniformly distributed among the various'plies.

The foregoing objects of my invention, and other objects which will become apparent as the description proceeds, are achieved bythe provision of a pneumatic tire including a plurality of rubberized cord fabric plies, and with the angle between the cords of each ply and the great circle of the tire being substantially greatest in the innermost ply and progressively less or periodically recurrently less in the radially outwardly positioned plies. Again, the principles of my invention may be achieved by a pneumatic tire casing comprising a carcass composed of a plurality of plies of rubberized cord fabric, the circumferential distance between the ends of any cord in an inner ply being less than the distance between the ends of any cord in any superimposed ply.

Or stated in terms of method, my invention includes correlating ply bias angles and/or ply 'pull-on stretches soV that a substantially uniform cured tire/cord angle gradient is provided in the builttire which results in uniform ply cocper.

ation.

For a better understanding of my invention reference should be had to the accompanying drawings wherein Fig; 1 is a perspective view of a section of one embodiment of a pneumatic tire constructed in accordance with my invention, and with parts thereof being broken away in steps; Fig. 2 is a diagrammatic plan view of the manner in which the plies of rubberized cord fabric are out from a length of cord fabric; Fig. 3 is a view similar to Fig. 2 .but illustrating the manner of cutting a plurality Yof plies on the same angle to form a band, and cutting a plurality of other plies on a different angle to form an additional band or bands; Fig. 4 is a diagrammatic show- -ing of a stepped down tire section built from the plies of Fig. 3; Figs. 5 and 6 are similar to Fig. 4 but illustrate other embodiments of my invention; Fig. 7 is a diagrammatic plan view of a ply of rubberized cord fabric illustrating the angle of the cords therein; and Fig. 8 is a diagrammatic side elevation of a section of a finished tire illustrating the position of the cords in the several plies thereof. l

Referring to the drawings, the letter T indicates generally one form of a pneumatic tire constructed in accordance with the principles of my invention. lSpecifically, the tire T includes therein illustrated diagrammatically the arrange'- superimposed plies of rubberized cord fabric i9, Il, I2, i3, Il, I5. I6, I1, I8, and I9. The fabric of each ply may be of the well known wei'tless or pickless type having the load bearing cords all extending in one direction and with the individual cords being held together only by the rubber skim or friction coating. Again, the fabric of each ply may be of the well known type in which the load bearing cords, usually called warp cords, extending in the same direction are held together by light weight weft or pick threads as employed here and in the claims is intended to include either of the two fabric types just described, or modiiications thereof. Usually each of the plies extends from edge to edge of the tire carcass and the side edges of the plies are positioned around inextensible bead portions 29, 2|, 22, and 23 in the tire embodiment illustrated, and with bead ipper and chater strips 245 and 25 being employed in known manner. Any usual breaker means 28 and 21 may be incorporated with thetire carcass on the periphery thereof, and the tire is provided with the usual tread portion 28 and rubber side walls 30.

Now in accordance with the principles of my invention each one of the plies Iii to I9 of the tire T is cut from a rubberized cord fabric strip at a progressively lesser bias angle (see Fig, 2) namely, ply I0 is cut at an angle of 52 between the cords and the center line of the ply, ply II at an angle of 51m-50'., ply I2 at an angle of 51-40', ply I3 at an angle of- 51-30, ply I4 at an angle of 51-20', ply I5 at an angle of '51-10, ply I6 at an angle of 51, ply I'I at an angle of 5050', ply I3 at an angle of 50-40, and ply I9 at an angle of 50-30'. The result is that the angle between the cords of each ply in the cured tire and the great circle of the tire decreases radially outwardly of the several plies of the tire. More specically, and referring to Fig. 1 of the drawings, ply IIJ for a given tire, for example a 9.00 x 20 tire, has a cured tire cord angle, i. e. the angle between the cord and the median plane or great Vcircle of the cured tire, of 40 degrees.

angle, for example 39%,; degrees, and plies I3 to I9 have angles of 391A, 39, 38%, 381/2, 38%, 38, and 37% degrees respectively. Thus, a tire structure is provided in which the cords of each ply have a less angle with the great circle of the tire in each radially outwardly positioned ply.

It should be particularly understood that it sometimes complicates the tire building operation to have every ply thereof cut at a different bias angle. Accordingly, I very often decrease the angle of the cord plies only at stepped points outwardly of the tire carcass, for example, I may make the first two plies from cord fabric cut at the same bias angle, the next two plies from cord fabric cut at a somewhat lesser bias angle, and so onfthroughout the tire. Again, I may make four or more plies of the tire from cord fabric cut at the same bias angle, the next four or more radially outwardly plies from cord fabric cut at a lesser bias angle, and so on throughout the tire.

Referring to Fig. 3 of the drawings, I have ment of the plies of a sixteen ply tire, for example a 16.00 x 24 tire. The first four plies 10 aisaeso y 6 tially (and each band to a greater amount) in being applied ,to the tire building form I obtain a i built tire carcass and a shaped tire `,carcass in I have found it consubstantially as a single ply, and in known mannel.

bias angle of approximately 491/2 degrees, and these four plies are formed into an individual band which has been designated in the drawing as the next outer band and which is then built onto the tire carcass. The nextv four plies 12 are cut on a bias angle of approximately 49 degrees and are also formed into a band which is built onto the tire carcass. The last four plies i3 are cut on a bias angle of approximately 48%; degrees and are also formed into a band which is built onto the tire carcass in the usual way. It will be understood that in the finished tire carcass the several plies forming-the same are usually positioned with the rubberized cords of every other ply extending in the same general direction and adjacent plies having the cords extending in opposite directions.

It will be recognized that when I decrease the angle between the ply cords and the great circle of the tire every two or four or more plies, as last described, the plies of the tire lying between the innermost ply of one band and the innermost ply of the next outer band may contain cords lying on an increased angle with the great circle of the tire. Although this is not desirable it is not highly objectionable and my compromise of reducing the angle for every band of two or more plies is a practical and workable expedient which can be adapted into production methods without undue bias cutting and fabric handling complications. For example, in the specific example of tire structure and bias angle change last given the cured tire cord angle of each ply from the innermost outwardly may be substantially: 38, 33-8', 38-16, 38-24', 37, 378', 37-l6, 37-24', 36, 36-8, 36-1d, mii-24', 35, 35-8, 35-16', 3524. Fig. a diagrammaticaliy illustrates this construction.

An important part of my invention is the provision of an improved method for building tires wherein and whereby I am able to control cured tire cord angles separate from, or in conjunction with, bias angle vchanges as heretofore described. Specifically, in the usual tire building operation wherein each ply in the tire is put on in turn, it has long been standard practice to wrap each ply in turn around the building form and tear off any surplus in the length of the ply.- This results in The next four plies 1I of the tire are cut on a Sil a tire carcass in which before shaping each ply has its cords lying at substantially the same angle to the great circle of the carcass. This carcass.

v when shaped, has thev cords of the several plies positioned at increased angles radially outwardly of the plies, as above described, and as disclosed and claimed in the prior art practices discussed. Now I have found that if the plies of the tire carcass are made up as separate bands/'of the same length, or preferably of successively shorter lengths, for example on a separate band building apparatus, and are then stretched circumferenwhich the angle between the cords of the several bands and the great circle of the tire decreases radially outwardly of thebands. In othenwords. by making the amount of pull-on stretch greater lfor each successive superimposed band, I am able to obtain substantially the same result which a decrease in bias angle produces.

Now when tires having a large number of plies are built, I have found it to be particularly advisable to use a combination of bias angle decrease and greater pull-on stretch in the plies.

This is because of limitations in factory practice as to the amount of pull-on stretch which can be conveniently handled, and because of the importance of controlling the cord count in the cured tire. Also, this practice minimizes the number of changes of bias angle required in any tire. For example, in a thirty ply tire the first ten plies may be cut at the same' bias angle and made into bands of the same lengthor successively shorter lengths and of two or more plies. Then successive bands are built onto the building form each with progressively greater pull-on stretch so that'after the tire is shaped the desired cured tire cord angle decrease or gradient is obtained in the vulcanized tire to give substantially uniform ply cooperation.

The ten plies of the second group are cut on a. smaller bias angle than the plies of the first group and made into bands of two or more plies and of the same length or successively shorter lengths. Then the successive bands are built onto the building form, each with progressively greater pull-on stretch so that the cured tire cord angie gradient decrease outwardly of the bands will be substantially the sameas and a continuation of the gradient decrease of the first ten plies. The ten plies forming the third and last group are cut on a still smaller bias angle than the second group and the band forming and progressively greater pull-'on stretch is repeated so that the vulcanized tire has a cured tire cord anglo lying on a, substantially uniform gradient from larger to smaller angles counting outwardly among the' bands.

. In the tire structure just described the cured tire cord angles using one ply bands may be respectively from the innermost ply outwardly approximately 38, 3750, 37-40, 37-30',

3310'. Fig. 5 illustrates diagrammatically such a tire construction, and wherein a substantially uniform reduction gradientdn cured tire cord angle is achieved throughout the tire outwardly of the plies by a combination of bias angle change plus progressively greater pull-on stretch. When aisaeao bias angle change in each ply, or the same reduction gradient can be obtained solely by progressively greater pull-on stretch. In conjunction with the use of progressively greater pull-on stretch alone or in combination with bias angle change, I preferably, but not necessarily,-employ mechanical or other stretching means to pre,- stretch the band before it goes to the tire builder so that the pull-on stretch in the building operation will be kept uniform for the convenience of thetire builder. However, it should be noted that too great pull-on stretches should be avoided because of the tendency to change the cord count per inch thereby.

It would be well to note here the sharp distinction that should be drawn at all times between bias angle (namely the angle between the ply cords and the center line of the ply as cut) and cured tire cord angle (above deilned). It is true that these angles bear a distinct relation to each other and means are known for determining the one from the other. In Fig. 7 I have diagrammatically shown a ply of rubberized cord fabric cut on a bias, with the bias angle between a given cord AB in the ply and the center line CL of the ply being 50 degrees. This ply will be, for example, the innermost ply in a tire carcass. The next radially outer or superimposed ply will be cut on a smaller bias angle, for example, the` position of the rubberized cord in the second ply of fabric is indicated by the line AB and the angle is an angle of say 49% degrees.

When the ply fabric illustrated in Fig. 7 is applied to a tire building form andis built into a tire, which is subsequently shaped to toric form and vulcanized therein, the cord will take substantially the position illustrated in Fig. 8 of the drawings by the dot and dash line indicated by the letter a, and the` circumferential distance between the ends of the cord becomes a distance p at the points of the tie-in of the cord with the beads of thel tire. A cord b in the next outward or superimposed ply of fabric, cut on a smaller bias angle as described in the'next proceeding paragraph, will take substantially the position shown in Fig. 8 of the drawings, and the distance between the ends of the cord b at the bead tie-in is substantially a distance q. A cord c in the next radially outward ply of fabric, cut on a still smaller bias angle, takes the position shown in Fig. 8, and the circumferential distance between the ends of the cord c at the point of bead tie-in becomes a vdistance r. A cord d in the next outer ply, cut on a still smaller bias angle takes a position as illustrated in Fig-8, and the circumferential distance between the ends of the cord d at the region of the bead tie-in becomes a distance s. It will be seen that s is greater than r, r is greater than q, and q is greater than p, so that, in describing my advance in the art, I may say lthat the circumferential distance between the bead tie-in of the rubberizedv cords in the several plies in a tire constructed in accordance with my invention increases radially outwardly of the plies of the tire, with the change being made in each ply or every two or more plies in successively outwardly positioned plies. 'And this is true whether the cord angle change is due to a progressive decrease in bias angle in the plies, due to a progressively greater pull-on stretch in the plies, or due to a combination thereof.

By way of an example of bias angle changes to achieve the objects of my invention, when building a tire of a size 24.00 x 32 and of thirtytwo ply construction, the rst band of four plies 8 may have a bias angle of 60 degrees, the second band of four plies a bias angle of 59% degrees, and succeeding bands, each of four plies, may have bias angles of 59, 581/2, 58, 571/2, 57, and 561/2 degrees respectively. f

A specic commercial application ofthe principles of my invention entailing a minimum of production complications comprises building a 24.00 x 32 tire of thirty-six ply construction and wherein the first eighteen plies are cut on a bias angle of 621/2 degrees and made into two-ply bands of the same length, namely 133.12 inches. Thus, each of the two-ply bands will be applied with greater pull-on stretch, The last eighteen plies are cut on a bias angle of 60 degrees and made into two-ply bands of the same length, namely 142.4 inches. Each of the last nine twoply bands are applied with greater pull-on stretch.

Again, in a commercial embodiment of a 16.00 x 24 tire of twenty plies, the first ten plies may be cut on a bias angle of 571/2 degrees. The plies are built into two-ply bands, with the first three bands being made of the same length, namely 109 inches long, and applied with progressively greater pull-on stretch. The next two bands are made 108 inches long, and are applied with greater pull-on stretch- The next ten plies are cut on a bias angle of 55 degrees and made into two ply bands. The first two bands are made of the same length, namely 114 inches, and are applied with progressively greater pull-on stretch. The last three bands are made of a shorter length, namely 113 inches, and are applied with progressively greater pull-on stretch.

So far as the exact cured tire cord angle is concerned, I have found that if the cured tire cord angle for the innermost ply of any given tire is selected in accordance with past experience or by any known methods, then the cured tire cord angle for each super-imposed ply should be'between about 5 and about 25 minutes less than the cured tire cord angle of the next inner ply, and usually about 10 or 12 minutes less. On occasions I have found it advisable to provide somewhat greater cord angle changes or gradients between plies, for example, up to 40 or slightly more for specialized constructions that may sometimes be required to be built, for the .time being, on standard building forms. With heavy plies the angle may be decreased closer to 25 minutes and with thin plies closer to 5 minutes, although ply thickness alone does not determine the pressure gradient. The most important criterion is surface curvature, and when the surface curvature of the tire carcass is small thegradient is usually nearer to 5', and when the surface curvature is large the gradient is usuallynearer to 25'. Surface curvature is dei'lned as the reciprocal of the radius of curvature of the cord path or 1 divided by the radius. Cured tire cord angle changes within the indicated llmits have been proven to give much more uniform ply cooperation and uniform cord loading over a wide range of tire sizes than has been achieved prior to my invention.

Or in terms of bias angle change, I have found that if the bias angle for the innermost ply is with thin plies or small surface curvatures closer to 2 minutes. Of course, when, because of production limitations, the bias angles of the various plies are advisably changed as groups or as bands, as above described, the change of bias angle in each band will be approximately the number of plies in the band times the decrease in angle for each ply as set forth in` this paragraph. l

It should be noted here that I am not more specific except in the examples given, as to the cured tire cord angle or the bias angle of the innermost ply. because my invention of uniform ply cooperation is not limited to any specific value or range of the cured tire cord angle or to the bias angle of the innermost ply. A carnpleted tire embodying the principles of my invention may have an innermost ply of any cord angle from large to small. In this respect it is old and well known that in some tires it is advisable to have a low cured tire cord angle, i.,e. angles down to 25 degrees or less, fcr example, to get a tire of low profile. Again, by keeping the cured tire cord angle high, i. e. up to 60 degrees or more, a tire of a different cross sectional contour is produced. The choice of representative or average angle in the tire is made from consideration of the service the tire is required to perform. But in any event, and regardless of the service requirements which determine the cured tire cord angle of the innermost ply, my invention is concerned with controlling and adjusting the cured tire cord angles along a gradient about any mean or starting value such that substantial uniformity of tension will be obtained in all plies.

Further, it should be noted that the blow-up of the tire from the shape in which it is built to the shape in which it is vulcanized and used has an -important bearing on cord tension and position. However, the objects of my invention are achieved as herein described as long as the relative lengths of the cords of the various plies are substantially the same on the building drum or core as the relative lengths of the cords of the various plies in the vulcanized tire. Experience has indicated proper core or drum construction for most of the standard tire sizes, and with the last above statement in mind proper core design for other tire sizes is not difficult,- and from cores or drums available that one best suited to a given building operation can be selected.

The term band as employed in the claims is intended to include one or more plies, and the term cord angle is intended tov mean the cured tire cord angle as above explained.

ticularly adapted to the manufacture of pneumatic tires having a very considerable plurality of plies and built from low stretch fabric.

It should be clearly recognized that the various examples of my invention which I have specifically set forth above are to the best of .my knowledge and belief proper and reasonably accurate; nevertheless in actual practice it is often very difcult to obtain in the cured tire an exact response to the theoretical angles desired or seemingly indicated by bias angles changes. In other words, the cured4 tire cord-angles may not in certain instances exactly follow the desired gradient pattern and this is due to factors which cannot be completely controlled, such as uneven fabric stretch, small angle changes, temperature variations, non-uniformity or variations in cord material, and other factors. The important thing is that a definite gradient trend is established in the 'direction described and set forth in detail above.

The term cord angle as employed in tbe specication and claims is intended to define the angle between the cords of a ply and the great circle of the tire lying in a plane normal to the axis of rotation of the tire. Further, the words superimposed ply or superimposed band utilized in the specification and claims are intended to mean a ply, plies, a band, or bands which are radially outside of previously recited ply, plies, band, or bands with or without being .in direct contact therewith. In other words, the principles cf the invention are not to be defeated or avoided merely by interposing a breaker strip or false ply orplies in the construction of a tire while following the basic teaching of this disclosure.

It will be understood that the term cord .fabric as utilized inthe specification and claims is intended to include weftless fabric, or thin and spaced weft cord fabric of conventional design, utilized in pneumatic tire construction, and the term.rubberized is to include natural or synthetic rubbers or plastics capable of use in pneumatic tire construction.

Therefore, the various specific tire examples, bias angles and cured tire cord angles shown in the drawings and above described are by way of I have found that when pneumatic tires are built in accordance with the principles herein .disclosed the tension developed in the cords during the shaping of the tires from the building shape is substantially unishape to the molded form, the amount of such tension being governed largely by the characteristics of the fabric used. Further, I have found that when a tire constructed in accordance with this invention is inflated and used each of the various plies in the tire is subjected tosubstantially uniform stress and is loaded so that each cord therein is subjected to substantially the same tension as any cord in any other ply of the tire. Accordingly, the tire can be constructed with the smallest number of plies to possess a given safety factor in any particular operation, and with each ply throughout the tire being uniformly stressed neither too high nor too low. The invention is parillustration only of the principles of my invention, and it should be particularly understood that I am not to be `limited thereto or thereby,

'but that the scope of my invention is deilned in the appended claims.

I claim:

1. A pneumatic tire including a plurality of rubberized cord fabric plies, and with the cord angle with the great circle of the tire of the innermost ply being greatest, and with the cord angle with the great circle of the tire being less in each superimposed ply.

2. A pneumatic tire including a plurality of rubberized cord fabric plies, and with the angle between the cords of each ply and the great circle of the tire being greatest adjacent the innermost ply and progressively less and less at outwardly stepped points in the plies.

3. A torio-shaped tire casing comprising a carcass composed of a plurality of plies of rubber.

' formed of plies having .cords making an angle with the great circlefof the tire greater than any other band, and each superimposed band being formed o1' plies having cords forming an angle with the great circle of the tire less than the angle of the plies oi the band it surrounds, the decrease in angle between bands being substantially equal to the product -oi the number oi' plies in the band multiplied by between about 2 minutes and `about 30 minutes.

5. A pneumatic tire including a carcass composed of a plurality oi bands of rubberized cord fabric, the innermost band having cord angles between its cords and the. great circle of the tire greater than any other band, and each superimposed band having cord angles less than the cord angles of the band it surrounds, the decrease in cord angle between bands being substantially equal to 'the product of -the number ciplies in the band multiplied 'by between about 5 minutes and about 4B minutes.

6. A pneumatic tire including a carcass composed oi' a plurality of bands of rubberized cord fabric, the innermost band having cord angles between its cords and the `great circle of the tire greater than any other band, and .eachsuperimposed band having cord angles less than the cord angles of vthe band it surrounds.

7. A pneumatic tire including a carcass corn r posed of .a plurality of bands fof rubberized cord fabric, the innermost band 'having a cord angle between its cords and the great circle of thetire greater than any other band, and each superimposed band having a cord :angle less than the cord angle of the band it surrounds, the decrease in cord angle between bands being substantially equal to the product of the number o1' plies in the band multiplied by about 10 minutes.

8. A vulcanized torio-shaped tire casing in- 1 cluding a carcass composed of a plurality oi bands of rubberized cord fabric, the circumferential distance between the ends of .any cord in any band being greater than the distance between the ends of any lcord `in substantially an radially inner band.

9. A vulcanized pneumatic tire including'a oarcassY portion formed :from a plurality of plies of rubberized fabric, the innermost ply having aV cord angle between its cords and the great circle or the tire of between about i3() and about 50 degrees, the next several superimposed plies having successively greater cord sangles, *the :next superimposed ply having a cord angle smaller 12 than'the cord angle o! the innermost ply, and

.the next several plies having successively greater 4 cord angles but less than the cord angle/o1' the 'u Number innermost plv.

1D. A pneumatic tire including a carcass por- 4 non formed or a plurality at pues or rubberized cord fabric, a. given ply having a cord angle between its cords :and the great circle of the tire oi between about 30 and about 60 degrees, a second Ply superimposed over the given ply and having a greater cord angle than ythe given ply, a third superimposed ply having a less cord angle than the :first ply, and a i'ourth superimposed ply having va greater cord angle than the third.

11. A vulcanized pneumatic tire including a carcass portion formed from a plurality of bands `oi. rubberized cord fabric, each band having a plurality of plies, the angle between the cords of the plies and the great' circle oi the tire in each superimposedband being less than the cord angles of the plies inthe band it surrounds, and

the cord angles in the plurality of plies of any band being smallest in the innermost ply and increasing in `each superimposed ply.

12. A pneumatic ire having a lcarcass consistof a plurality of :fabric plies, at least a maj ority of the plies having cords which make van angle with the great ycircie of the tire which decreases outwardly of the plies.

13. A pneumatic ltire having a carcass consistl ing of a plurality of fabric plies, at least a majority of the plies having cords which .make an angle with the `great circle oi the tire which ldecreases outwardly of the plies, land at least a majority ci the plies adjacent to each other being positionedso that rtheir cords are directed at opposite angles.

JOM F. lURDY.

REFERENCES curan lThe following .references are of record in the :me of this patent:

STATES PATENTS -Name Date Kratz Sept. 5, i922 Hopldnson May 13, w24 Fording July 1.1;, 15922 Dickinson .May 8, i923 Marks Dec.'27, i964 May 30, w05 Keith Apr. 6, m26 Marks May 30, 1965 Denman Jan. .2, 1917 

